Manipulating charge density waves in1T−TaS2by charge-carrier doping: A first-principles investigation

Abstract

The transition metal dichalcogenide (TMD) 1T -TaS2 exhibits a rich set of charge density wave (CDW) orders. Recent investigations suggested that using light or electric field can manipulate the commensurate (C) CDW ground state. Such manipulations are considered to be determined by the charge carrier doping. Here we simulate by first-principles calculations the carrier doping effect on CCDW in 1T -TaS2. We investigate the charge doping effects on the electronic structures and phonon instabilities of 1T structure and analyze the doping induced energy and distortion ratio variations in CCDW structure. We found that both in bulk and monolayer 1T -TaS2, CCDW is stable upon electron doping, while hole doping can significantly suppress the CCDW, implying different mechanisms of such reported manipulations. Light or positive perpendicular electric field induced hole doping increases the energy of CCDW, so that the system transforms to NCCDW or similar metastable state. On the other hand, even the CCDW distortion is more stable upon in-plain electric field induced electron injection, some accompanied effects can drive the system to cross over the energy barrier from CCDW to nearly commensurate (NC) CDW or similar metastable state. We also estimate that hole doping can introduce potential superconductivity with Tc of 6 ∼ 7 K. Controllable switching of different states such as CCDW/Mott insulating state, metallic state, and even the superconducting state can be realized in 1T -TaS2, which makes the novel material have very promising applications in the future electronic devices.

Ab initio phonon self-energies and fluctuation diagnostics of phonon anomalies: Lattice instabilities from Dirac pseudospin physics in transition metal dichalcogenides

“…Charge doping is known to affect CDW instabilities by shifting the ordering wave vectors and suppressing or supporting CDW order in many materials from high-T c superconductors [4] to TMDCs [44,[81][82][83][84] and 1H-TaS 2 in particular [62,66,85,86]. We studied the dependence of the LA phonon mode on charge doping in the phonon self-energy formalism [Eqs.…”

Evidence for a thermally driven charge-density-wave transition in 1T-TaS2 thin-film devices: Prospects for GHz switching speed

“…CDW transitions can be induced by various perturbations, including heating, 9 doping, [10][11][12][13][14] electrical pulsing, 15-17 substrate effects, 18 gate biasing, 17,19,20 and alteration of the thickness of the material. [21][22][23] The 1T polymorph of TaS2 is one of the 2D van der Waals materials of the transition-metal dichalcogenide (TMD) group that reveals phase transitions in the form of abrupt resistivity changes and hysteresis.…”

Controllable phase transitions between multiple charge density waves in monolayer 1T-VSe2 via charge doping

“…doping changes the Fermi surface of VSe2 from the previous cigar-like electron pockets to nearly triangular hole pockets centered at the K points of the first BZ, due to the raise of the Fermi level. Besides, an extra band compared with the band structure of pristine monolayer VSe2 appear around the Fermi level 37 and forms a small electron pocket at 𝛤 point as shown in the Fermi surface. It is noted that the nesting conditions for the 𝑞 2 and 𝑞 3 vectors, which correspond to the √7 × √3 CDW, are not satisfied in this doping concentration as the highlighted orange arrows shown in Fig.…”